DE69609721T2 - COMPOSITION FOR A RAILWAY MATERIAL FOR INK JET RECORDING - Google Patents

Description

Field of the invention

The invention relates to an uncrosslinked composition suitable for use as an inkjet recording medium and to a polymeric recording sheet having such compositions applied thereto and subsequently crosslinked, thereby rendering such sheet suitable for imaging in an inkjet printer.

Description of the field

Imaging devices such as ink jet printers and pen plotters are established methods for printing various information, including labels and multi-color graphics. The presentation of such information has created a need for ink-receptive imageable receptors, particularly transparent receptors used as overlays in engineering drawings and as transparent films for overhead projection. Imaging, either with the ink jet printer or the pen plotter, involves the deposition of ink on the surface of these transparent receptors. These imaging devices typically use inks that can remain exposed to air for extended periods of time without completely drying. Since it is desirable that the surface of these receptors be quickly dry and non-tacky to the touch after imaging, even after absorbing significant amounts of liquid, it is desirable that transparent imaging materials be capable of absorbing significant amounts of liquid and yet retaining a certain degree of durability and transparency.

The creation of an image by an inkjet printer results in large amounts of solvent, generally mixtures of glycols and water, remaining in the imaged areas. The diffusion of this solvent into unimaged areas can cause the image to "bleed" if the dye is carried along with the solvent.

U.S. Patent No. 5,141,797 discloses opaque ink jet recording webs comprising a water soluble polymeric binder, a titanium chelate crosslinker, and a high absorbency inorganic filler, e.g., silica. This filler is present in a ratio to the polymeric binder of from 2:1 to 7:1. Paper substrates are preferred. Only single layer coatings are disclosed.

A method for improving drying and reducing drying time is disclosed in the liquid absorbent materials disclosed in U.S. Patent No. 5,134,198. These materials include crosslinked polymeric compositions capable of forming continuous matrices for liquid absorbent semi-interpenetrating polymer networks. These networks are mixtures of polymers wherein at least one of the polymeric components is crosslinked after mixing, thereby forming a continuous network throughout the volume of the material which entangles the uncrosslinked polymeric components to produce a macroscopically homogeneous composition. Such compositions are useful for producing durable, ink-absorbing, transparent graphic materials which do not have the disadvantages of the materials listed above.

WO 8806532 discloses a transparent recording film and an aqueous manufacturing process. The transparent film is coated with a hydroxyethyl cellulose polymer or a mixture of polymers. The coating solution may also contain a surfactant to promote leveling and adhesion to the surface and alumina hydrate to impart a pencil roughness to the surface.

U.S. Patent No. 5,277,965 discloses a recording medium comprising a base film having an ink-receptive layer on one surface and a heat-absorbing layer on the other, and an anti-curl layer coated on the surface of the heat-absorbing layer. The materials suitable for the ink-receptive layer may include hydrophilic materials such as binary mixtures of polyethylene oxide with any of the following: hydroxypropylmethylcellulose (methocel), hydroxyethylcellulose; water-soluble ethylhydroxyethylcellulose, hydroxybutylmethylcellulose, hydroxypropylcellulose, methylcellulose, hydroxyethylmethylcellulose; vinyl methyl ether/maleic acid copolymers, acrylamide/acrylic acid copolymers; salts of carboxymethyl hydroxyethyl cellulose; cellulose acetate, cellulose acetate hydrogen phthalate, hydroxypropyl methyl cellulose phthalate; cellulose sulfate; PVA; PVP; vinyl alcohol/vinyl acetate copolymer, etc.

U.S. Patent No. 5,068,140 discloses a transparent film consisting of a supporting substrate and an anti-curl coating or coatings thereunder. In a particular embodiment, the transparent film comprises an anti-curl coating comprising two layers. The color-receiving layer comprises, in one embodiment, blends of polyethylene oxide, blends of polyethylene oxide with cellulose, such as sodium carboxymethyl cellulose, hydroxymethyl cellulose, and a component selected from (1) vinyl methyl ether/maleic acid copolymer; (2) hydroxypropyl cellulose; (3) acrylamide/acrylic acid copolymer; (4) sodium carboxymethyl hydroxyethyl cellulose; (5) hydroxyethyl cellulose; (6) water-soluble ethyl hydroxyethyl cellulose; (7) cellulose sulfate; (8) polyvinyl alcohol; (9) polyvinylpyrrolidone; (10) poly(acrylamido-2-methylpropanesulfonic acid); (11) Poly(diethylenetriamine-co-adipic acid); (12) Polyimidazoline, quaternized; (13) Poly(N,N-methyl-3-S-dimethylenepiperidinium chloride); (14) Poly(ethyleneimine)epichlorohydrin, modified; (15) Polyethylenimine, ethoxylated; Blends of Poly(cc-methylstyrene) with a component comprising a chlorinated compound.

U.S. Patent No. 4,554,181 discloses an ink jet recording sheet having a single layer coated on a substrate. The coating, which may be on paper or film substrates, contains two main components; a mordant and a water-soluble salt of a polyvalent metal. The mordant is a cationic polymer material designed to react with an acid residue present on a dye molecule. The water-soluble salt of the polyvalent metal may be derived from a wide range of metals, namely those of Group II, Group III and the transition metals of the Periodic Table of the Elements. Salts specifically mentioned include calcium formate, aluminum chlorohydrate and certain zirconium salts. A two-layer system is not disclosed.

US Patent No. 4,141,797 discloses inkjet papers with crosslinked binders and opaque layers. The opacity is achieved by using a paper pulp and by including an inorganic filler in the coated layer. A titanium chelate crosslinker is also disclosed. Tyzor® TE is specifically mentioned. Three other patents, ie US Patent Nos. 4,609,479, 3,682,688 and 4,690,479, disclose the generic use of titanium compounds as crosslinkers. Binder polymers, including gelatin materials, are disclosed, as is the use of a mordant.

U.S. Patent No. 4,781,985 discloses a film support having a coating thereon, wherein the coating contains one of two possible general structures of ionic fluorocarbon-type surfactants. One of these two general structures is characterized by a quaternary ammonium compound with a side chain containing a sulfide bond; the other general structure contains the element phosphorus. It is disclosed that other fluorochemical surfactants do not provide the advantages of these two structures. No two-layer coating systems are disclosed.

US Patent No. 5,429,860 discloses an ink/media combination intended to achieve an excellent final copy by developing an ink matched to the film and vice versa. An external energy source is used to perform a fixing step after the ink has been brought into contact with the media. At least one polyvalent metal salt Tyzor® 131, as well as generic organic titanates are disclosed.

U.S. Patent Nos. 5,045,864 and 5,084,340 disclose single layer imaging elements comprising a dye receptive layer containing 50-80% of a specific particulate polyester material, i.e., poly(cyclohexylenedimethylene-co-oxydiethylene isophthalate-co-sodium sulfobenzenedicarboxylate), 15-50% vinylpyrrolidone, and minor amounts of a short chain alkylene oxide homopolymer or copolymer, a fluorochemical surfactant, and inert particles.

The inventors have now discovered that an ink jet film comprising a single layer or a thick absorptive underlayer and an optically clear, thin top layer containing certain nonionic surfactants and a metal chelate provides high density images which are tack-free, durable and exhibit substantially no ink bleed.

Summary of the invention

The invention provides a composition suitable for use on an ink jet recording sheet, an ink jet recording sheet having on at least one major surface the composition composition, and an inkjet recording sheet having a two-layer coating structure.

Uncrosslinked compositions of the invention include

a) at least one non-ionic surfactant of the fluorocarbon type selected from linear perfluorinated polyethoxylated alcohols, fluorinated alkylpolyoxyethylene alcohols and fluorinated alkyl alkoxylates,

b) at least one metal chelate selected from titanate alkanolamines, titanate acetonates, aluminium alkanolamines and zirconium alkanolamines and

c) at least one cellulose polymer selected from hydroxycellulose polymers and polymers of substituted hydroxycellulose,

such a composition being crosslinkable when exposed to temperatures of at least 90ºC.

Ink jet recording sheet materials of the invention comprise a substrate having two major surfaces, at least one major surface having coated thereon a composition comprising a nonionic fluorocarbon-type surfactant selected from linear perfluorinated polyethoxylated alcohols, fluorinated alkyl polyoxyethylene alcohols and fluorinated alkyl alkoxylates, at least one metal chelate selected from titanate alkanolamines, titanate acetonates, aluminum alkanolamines and zirconium alkanolamines, and at least one cellulosic polymer selected from hydroxycellulose polymers and polymers of substituted hydroxycellulose, wherein the composition has been crosslinked to the substrate.

Preferred ink jet recording webs of the invention include an ink jet recording web comprising an imageable two-layer coating comprising:

a) a thick absorbent backing comprising at least one crosslinkable polymeric component and

b) an optically clear, thin topcoat comprising the above composition, wherein the topcoat has been crosslinked to the substrate by the application of heat.

Preferred two-layer coatings include

a) a thick absorbent backing comprising

i) at least one crosslinkable polymeric component;

ii) at least one liquid-absorbing component comprising a water-absorbing polymer and

iii) 0 to 5% of a crosslinker

b) an optically clear, thin top layer comprising

i) 0.05% to 6% of at least one of the above-mentioned non-ionic fluorocarbon-type surfactants,

(ii) 14% to 94% of a hydroxycellulose polymer or polymer of substituted hydroxycellulose,

iii) 5% to 80% of a metal chelate as mentioned above.

The following terms, as used here, have the following meanings:

1. The term "semi-interpenetrating network" means an entanglement of a homocrosslinked polymer with a linear uncrosslinked polymer.

2. The term "SIPN" refers to a semi-interpenetrating network.

3. The term "mordant" means a compound which, when present in a composition, interacts with a dye, thereby preventing diffusion through the composition.

4. The term "crosslinkable" means capable of forming covalent or strong ionic bonds with itself or with a separate agent added for this purpose.

5. The term "hydrophilic" is used to describe a material that is generally absorbent of water, either in the sense that its surface is wettable by water or in the sense that the volume of the material is capable of absorbing significant amounts of water. Materials that exhibit surface wettability by water have hydrophilic surfaces. Monomer units are said to be hydrophilic if they have a water uptake capacity of at least one mole of water per mole of monomer unit.

6. The term "hydrophobic" refers to materials whose surfaces are not readily wettable by water. Monomer units are called hydrophobic if, when polymerized with themselves, they form water-insoluble polymers that can only absorb small amounts of water.

7. The term "chelate" refers to a coordination compound in which a central metal ion is bound by coordinate bonds to two or more non-metallic ions. which form heterocyclic rings, with the metal ion being a part of each ring.

8. The term "surfactant" refers to a compound that reduces surface tension, thereby increasing surface wetting.

9. The term "optically clear" means that most of the light passing through is not scattered.

All parts, percentages and ratios herein are by weight unless expressly stated otherwise.

Detailed description of the invention

Compositions of the invention are suitable for application to web materials for ink jet recording. Such compositions are crosslinkable using heat and comprise at least one metal chelate selected from titanatelkanolamines, titanate acetonates, aluminum alkanolamines and zirconium alkanolamines, at least one nonionic fluorocarbon-type surfactant selected from linear perfluorinated polyethoxylated alcohols, fluorinated alkyl polyoxyethylene alcohols and fluorinated alkyl alkoxylates, and at least one cellulosic polymer selected from hydroxycellulose polymers and substituted hydroxycellulose polymers, such composition being crosslinkable when exposed to temperatures of at least 90°C.

The above metal chelates typically do not undergo immediate hydrolysis when mixed with cross-linkable materials, but remain non-reactive unless activated by increasing the temperature, which begins to break down the structure of the chelate. The exact temperature required depends on the activity of the other components with which the chelate is mixed and the functional groups on the metal chelate.

Aluminium and titanate-containing chelates are preferred, with titanate triethanolamine chelates being highly preferred.

It is believed that the metal chelates do not undergo solvolysis when combined with the other ingredients, but rather begin to crosslink when heated during drying of the film. The chelates are complexed, whereby the chelates provide titanate metal ions which then complex with a hydroxycellulose material and convert into the corresponding metal oxide or hydroxide in the The metal ions then react further with the alkanolamine, which regenerates the titanate alkanolamine chelates in hydroxylate form. The solvolysis profile is shown below.

Commercially available chelates include titanate triethanolamine chelate, available as Tyzor® TE, and titanate acetylacetonate chelate, Tyzor® GBA, available from E. I. DuPont de Nemours (DuPont).

Suitable nonionic fluorocarbon-type surfactants are those having at least one slightly hydrophilic portion and one hydrophobic portion. Suitable surfactants include linear perfluorinated polyethoxylated alcohols, fluorinated alkyl polyoxyethylene alcohols and fluorinated alkyl alkoxylates.

Preferred nonionic fluorocarbon surfactants are those with one strongly hydrophilic end and one strongly hydrophobic end. The hydrophobic end allows effective leakage at the surface of the coated layer and the hydrophilic end provides a high surface energy moiety on the surface which interacts with water-based inks to produce uniform images. Preferred surfactants are fluorinated polyethoxylated alcohols.

Commercially available nonionic surfactants include fluorochemical surfactants such as the perfluorinated polyethoxylated alcohols, available as Zonyl FSO®, Zonyl FSN® and the 100% pure versions thereof, Zonyl FSO-100®, which has the following structure:

RfCH2 CH2 (CH2 CH2 O)1-18 OH

Rf=F(CF2 CF2 )2-10

and Zonyl FSN-100®, from DuPont; and the fluorinated alkyl polyoxyethylene alcohols, available as Fluorad® FC-170C, which has the following structure:

and Fluorad® 171C, available from Minnesota Mining and Manufacturing Company (3M), which can be represented as follows:

Although the preferred amount will vary with the particular nonionic fluorocarbon-type surfactant used, the compositions of the invention typically comprise up to 10%, preferably 0.05% to 6% of the surfactant. When a fluorocarbon-type surfactant comprising a polyethoxylated alcohol is used, the composition preferably comprises 0.5% to 3% of the surfactant.

Ink jet recording sheet materials of the invention comprise a substrate having coated thereon a single layer comprising the essential ingredients of the compositions of the invention. The single layer compositions of the invention must comprise at least one metal chelate selected from titanate alkanolamines, titanate acetonates, aluminum alkanolamines and zirconium alkanolamines, at least one fluorocarbon-type nonionic surfactant selected from linear perfluorinated polyethoxylated alcohols, fluorinated alkyl polyoxyethylene alcohols and fluorinated alkyl alkoxylates, and at least one cellulosic polymer selected from hydroxycellulose polymers and polymers of substituted hydroxycellulose.

The composition is not crosslinked prior to application to the sheet, but is applied in the form of the uncrosslinked composition described above, and is crosslinked after application by the application of heat. This is typically done in a drying oven. Without wishing to be bound by theory, it is believed that the nonionic fluorine-type surfactant leaches out at the surface after application. Some aging of the recording sheet is therefore preferred. This both provides improved optical density properties and allows the hydrophilic portion of the surfactant to carry the large ink drops used in ink jet imaging through the layer where they can be absorbed. If the composition were crosslinked prior to application, the surfactant would be trapped in the crosslinked network, which would require a much higher concentration for any to be present at the surface.

Preferred single layer ink jet recording sheet materials of the invention comprise 0.05% to 6% of the above-mentioned fluorocarbon type nonionic surfactant, 5% to 80% of the above-mentioned metal chelate, and at least one cellulosic polymer selected from hydroxycellulose polymers and substituted hydroxycellulose polymers such as hydroxyethylcellulose, hydroxypropylmethylcellulose, and the like.

Such a single layer coating may also contain additional adjuvants such as mordanting agents, polymeric microspheres, anti-curl agents such as polyethylene glycols, and the like.

Preferred ink jet recording sheet materials of the invention comprise a two-layer coating system including an optically clear top layer and an ink absorbing bottom layer.

The topsheet is an optically clear thin layer comprising at least one fluorocarbon-type nonionic surfactant, a metal chelate and at least one hydroxycellulose polymer or polymer of substituted hydroxycellulose as described above.

Top layers of the invention comprise 5% to 80% of the metal chelate, preferably 5% to 35%.

The topsheet also comprises at least 14% to 94% of a hydroxycellulose polymer. Suitable hydroxycellulose materials include hydroxymethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, and the like. Such materials are commercially available, e.g., as Methocel® series, designated A, E, F, J, K, and the like, e.g., Methocel® F-50, from the Dow Chemical Company.

For the purpose of improving handling and flexibility, the topcoat may also contain particles such as polymeric microspheres or beads, which may be hollow or solid. Preferred particulate materials are made from polymeric materials such as polymethyl methacrylate, poly(stearyl methacrylate)hexanediol diacrylate copolymers, polytetrafluoroethylene or polyethylene; starch and silica. Polymethyl methacrylate beads are most preferred. The amounts of particles are limited by the requirement that the final coating be transparent with a haze level of no more than 15% as measured according to ASTM D 1003-61 (reaffirmed 1979). The preferred mean particle diameter for the particulate material is 5 to 40 microns, with at least 25% of the particles having a diameter of 15 microns or more. Most preferably, at least about 50% of the particulate material has a diameter of 20 to 40 µm.

The absorbent backsheet comprises a polymeric ink-receptive material. Although at least one of the polymers present in the polymeric ink-receptive material is preferably crosslinkable, the system need not be crosslinked to exhibit the improved longevity and reduced bleed. Such crosslinked systems are advantageous for dry time as disclosed in U.S. Patent No. 5,134,198 (Iqbal).

The backsheet preferably comprises a polymer blend comprising at least one water-absorbing hydrophilic polymeric material and at least one hydrophobic polymeric material containing acid functional groups. The uptake capacities of various monomer units are given, for example, in D. W. Van Krevelin, with the collaboration of P. J. Hoftyzer, "Properties of Polymers: Correlations with Chemical Structure," Elsevier Publishing Company (Amsterdam, London, New York, 1972), pp. 294-296. Commercially available polymers include "Copolymer 958," a poly(vinylpyrrolidone/dimethylaminoethyl methacrylate) available from GAF Corporation, and the like.

The water-absorbing, hydrophilic polymeric material comprises homopolymers or copolymers of monomer units selected from vinyl lactams, alkyl tert-aminoalkyl acrylates or methacrylates, alkyl quart-aminoalkyl acrylates or methacrylates, 2-vinylpyridine and 4-vinylpyridine. The polymerization of these monomers can be carried out by free radical methods, with conditions such as time, temperature, ratio of monomer units and the like being adjusted to obtain the desired properties of the final polymer.

Hydrophobic polymeric materials are preferably derived from combinations of acrylic or other hydrophobic ethylenically unsaturated monomer units copolymerized with monomer units having acid functionality. The hydrophobic monomer units can form water-insoluble polymers when polymerized alone and do not contain side chain alkyl groups with more than 10 carbon atoms. They can also be copolymerized with at least one species of acid functional monomer units.

Preferred hydrophobic monomer units are preferably selected from certain acrylates and methacrylates, e.g. methyl methacrylate, ethyl methacrylate, acrylonitrile, styrene or α-methylstyrene and vinyl acetate. Preferred acid functional units for polymerization with the hydrophobic monomer units are acrylic acid and methacrylic acid in amounts of 2% to 20%.

In a preferred embodiment, the undercoat coating is a semi-interpenetrating network (SIPN). The SIPN of the present invention comprises crosslinkable polymers which are either hydrophobic or hydrophilic in nature and which are obtained from the copolymerization of acrylic or other hydrophobic or hydrophilic ethylenically unsaturated monomer units with monomers having acid groups or, if already having ester groups in side chains in these acrylic or ethylenically unsaturated monomer units are present can be derived from hydrolysis. The SIPN for this ink-receptive coating would be prepared from polymer blends comprising at least one crosslinkable polyethylene-acrylic acid copolymer, at least one hydrophilic liquid-absorbing polymer and optionally a crosslinker. The SIPN are continuous networks with the crosslinked polymer forming a continuous matrix as disclosed in U.S. Patent Nos. 5,389,723, 5,241,006, 5,376,727.

SIPNs preferably used to make backsheet layers of the present invention comprise 25 to 99% crosslinkable polymer, preferably 30 to 60%. The liquid absorbing component may comprise 1 to 75%, preferably 40 to 70% of the total SIPN.

The crosslinker is preferably made from multifunctional aziridines which have at least two crosslinking sites per molecule, such as trimethylolpropane tris(β-(N-aziridinyl)propionate), Pentaerythritol - tris(β-(N-aziridinyl)propionate), Trimethylolpropane tris(β-(N-methylaziridinyl)propionate)

etc. The crosslinker, when used, comprises 0.5 to 6.0%, preferably 1.0 to 4.5%.

The undercoat may also comprise a mordant to reduce color fading and bleeding. The mordant, when present, preferably comprises from 1 part to 20 parts by weight of the solids, more preferably from 3 parts to 10 parts by weight. Suitable mordants include polymeric mordants having at least one guanidine functionality.

The undercoat formulation can be prepared by dissolving the components in a common solvent. Known methods for selecting a common solvent make use of the Hansen parameters as described in U.S. Patent No. 4,935,307.

The two layers can be applied to a film substrate by any conventional coating method, e.g., depositing from a solution or dispersion of the resins in a solvent or aqueous medium or a mixture thereof by methods such as Meyer bar coating, knife coating, reverse roll coating, gravure coating, and the like. The base layer is preferably applied to a thickness of 0.5 µm to 10 µm and the top layer preferably has a thickness of 0.5 µm to 10 µm.

The layers can be dried by conventional drying methods, e.g., by heating in a hot air oven at a temperature appropriate for the particular film substrate chosen. However, the drying temperature must be at least about 90°C, preferably at least about 120°C, to crosslink the metal chelate and create the colloidal gel with the hydroxycellulose polymer.

To improve processing, additional additives may also be incorporated into one or both layers, including thickeners such as xanthan gum, catalysts, adhesion promoters, glycols, antifoam agents, antistatic materials, and the like. Additives such as the mordant may also be present in the topcoat rather than the basecoat or in both layers. One additive that may be present in the bottomcoat to control curl is a plasticizing compound. Suitable compounds include, for example, low molecular weight polyethylene glycols, polypropylene glycols or polyethers; e.g., PEG 600, Pycal® 94 and Carbowax® 600.

Film substrates can be made from any polymer capable of forming a self-supporting film, for example films made from cellulose esters such as Cellulose triacetate or diacetate, polystyrene, polyamides, vinyl chloride polymers or copolymers, polyolefin and polyallomer polymers and copolymers, polysulfones, polycarbonates and polyesters. Suitable polyester films can be made from polyesters obtained by condensing one or more dicarboxylic acids or their lower alkyl diesters in which the alkyl radical contains up to 6 carbon atoms, e.g. terephthalic acid, isophthalic acid, phthalic acid, 2,5-, 2,6- and 2,7-naphthalenedicarboxylic acid, succinic acid, sebacic acid, adipic acid, azelaic acid, with one or more glycols, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol and the like.

Preferred film substrates are cellulose triacetate or cellulose diacetate, polyester, especially polyethylene terephthalate, and polystyrene films. Polyethylene terephthalate is most preferred. It is preferred that film substrates have a thickness in the range of 50 µm to 125 µm. Film substrates with a thickness of less than 50 µm are difficult to handle using conventional graphic materials processes. Film substrates with thicknesses over 125 µm are very stiff and cause feeding difficulties in certain commercially available ink jet printers and pen plotters.

Substrates may be opaque, transparent or translucent depending on the intended use, e.g., transmission projection, reflection projections or single copies for brochures and the like. If an opaque substrate is desired, the substrate may be a film as described above with pigmented fillers, or it may be a microvoided surface such as a paper or fabric surface.

When polyester or polystyrene film substrates are used, they are preferably biaxially oriented and may also be heat set for dimensional stability during bonding of the image to the support. These films may be made by any conventional process in which the film is biaxially stretched to achieve molecular orientation and made dimensionally stable by heat setting.

To enhance the adhesion of the undercoat layer to the film substrate, it may be desirable to treat the surface of the film substrate with one or more primers, in a single or multiple coats. Suitable primers include those known to have a swelling effect on the film substrate polymer. Examples include halogenated phenols dissolved in organic solvents. In a In another embodiment, the surface of the film substrate can be modified by a treatment such as corona treatment or plasma treatment.

The primer layer, if used, should be relatively thin, preferably less than 2 µm, most preferably less than 1 µm thick, and can be applied by conventional coating techniques.

Transparent films of the invention are particularly useful in the manufacture of image transparencies for viewing in transmission mode, e.g. in conjunction with an overhead projector.

The following examples are for illustrative purposes and do not limit the scope of the invention, which is defined by the claims.

Measuring method Image density

Transmissive image density is measured by imaging the desired color and measuring it using a Macbeth® TD 903 densitometer with the Gold and Status A filters. Black image density is determined by measuring the density of a solid black filled rectangular image.

dry season

The environmental conditions for this test are 70ºC and 50% relative humidity (RH). The print pattern consists of solid filled columns of adjacent colors. The columns are 0.64 cm to 1.27 cm wide and 15-23 cm long. After printing, the material is placed on a flat surface and then brought into contact with document paper. A 6.3 cm wide 2 kg rubber roller is then rolled over the paper twice. The paper is then removed and the drying time DT is calculated using the following formula:

DT = TD + (LT/LP)TP

where TD is the time period between the end of printing and the bringing of the image into contact with the document paper; LT is the length of the image transferred to paper; LP is the length of the columns printed; and TP is the printing time.

Surface energy

The surface energy values are checked using a Wilhelmy meter, model DCA-322. The test is carried out at ambient temperature and the meter is operated at a speed of 136 um/60 s (min) over a distance of 20 mm.

Samples are prepared by cutting two pieces of coated film, applying adhesive to the back of a piece using a Scotch® Permanent Adhesive Glue Stick, and adhering the pieces back to back with finger pressure for several minutes, taking care not to touch the coated area. Samples are allowed to dry overnight before measurements. Measurements are made using three liquids for safety, requiring a polar liquid (HPLC grade water) with a surface energy of 72.8 dynes/cm and a non-polar liquid, hexadecane (99+% purity, from Aldrich Chemical) with a surface energy of 48.3 dynes/cm; ethylene glycol (99.8% from Aldrich Chemical) was used as a third liquid.

The sample is placed on a plate and brought into contact with the liquid. The additional force resulting from the surface tension is measured. Identical samples are brought into contact with each of the liquids and the surface energy of the sample is calculated.

Examples Example 1 and comparative examples C2 and C3

A single layer having the undercoat composition below was coated onto a primed polyester substrate and then dried at 100°C for 120 seconds (2 minutes). The topcoat described below, containing the nonionic surfactant and the metal chelate, was then coated onto the undercoat to a wet thickness of 75 µm and dried at 100°C for 60 seconds (1 minute). This was Example 1.

A second sample of the undercoat composition was coated and then dried at 100°C for 120 seconds (2 minutes). This single-layer recording sheet was Comparative Example C2.

Finally, a third sample of the undercoat composition was coated to a wet thickness of 75 µm with a topcoat containing a metal chelate of the invention, i.e., triethanolamine titanate chelate, but no nonionic surfactant, and then dried in an oven at 120°C for 60 seconds (1 minute). This was Comparative Example C2.

The inkjet sheets were then imaged on an Epson Color Stylus® printer; in two tests, Example C2 had a black density of only 0.65, Example C3 had a black density between 0.80 and 0.84, Example 1 had a black density between 0.90 and 0.94.

It can be seen that the black density of the two-layer coating system with metal chelate (but without nonionic surfactant) was improved over the single-layer coating containing neither the metal chelate nor the nonionic surfactant, but the two-layer coating of Example 1 containing both the nonionic surfactant and the metal ion chelate had a black density that was greatly improved over both comparative examples.

The mordant disclosed below has the following structure:

where n is an integer of at least 2.

Examples 3-9

These examples show the change in black density in the film of Example 1 with varying amounts of the fluorosurfactant Zonyl® FSO. The films were imaged in an Epson Color Stylus® printer and the densities were measured under ambient conditions with a densitometer.

Example 10

The undercoat was coated as described in Example C2 and over the undercoat was coated a topcoat containing a metal chelate of the invention, ie an aluminum triethanolamine chelate, and a nonionic surfactant to a wet thickness of 75 µm and dried at 120°C for 60 s (1 min).

Examples 11-15

These examples show how the black density in the film with the composition of Example 10 changes with the amounts of the fluorosurfactant Zonyl® FSO.

Examples 16-19

These examples have the same composition as Example 10 except that the Zonyl® FSO was replaced with 3M's FC 170C fluorosurfactant. The following table shows the change in black density when the amount of fluorosurfactant is varied.

Examples C20 and C21

These examples show the effect of various fluorosurfactants used at 1%. This is a two-layer system with the undercoat exactly the same as in Example C2 except that the surfactants used were Zonyl® FSA and Zonyl® FSJ. Both are anionic surfactants available from DuPont. Example 4, which uses a nonionic surfactant at 1%, is provided as a comparative example. As can be seen from the data, high black density values are not obtained when using the anionic fluorosurfactants compared to using the nonionic surfactants.

Examples 23-28

These examples show the influence of different fluorine-containing surfactants with different hydrophobic residues on the black density using the composition of Example 10.

It can be seen that the anionic surfactants did not provide increased black density. Zonyl® TM, a fluorocarbon methacrylate monomer having the structure

is a non-ionic surfactant, however, ink jet recording sheets containing this composition in the coating did not provide increased black density values. It is believed that the surfactant does not contain enough hydrophilicity to rapidly draw the ink into the coating and increase the density.

Examples 29-31

These examples illustrate the influence of various fluorocarbon surfactants containing different hydrophilic moieties on the black density of the film of Example 1. These Fluorad® surfactants, available from 3M, are nonionic with the same fluorocarbon tail but different hydrophilic moieties.

Fluorad® FC-430, which has the following structure,

does not provide a density increase. This is a very large molecule with very little fluorocarbon present relative to the large polymer. It is believed that this nonionic surfactant is not hydrophobic enough to leach out at the surface of the topsheet and that this leachout is further hindered by the size of the polymer.

Example 38 and comparative examples C39-C45

The undercoat in each of the following examples was machine coated onto 100 µm polyvinylidene chloride (PVDC) primed polyethylene terephthalate to give a dry coating weight of 9.7 g/m². The coating comprises 29.6% polyvinyl alcohol available as Airvol® 523 from Air Products, 5.2% of a polyvinyl alcohol with a different hydrolysis number available as Gohsenol® KP06 from Nippon Synthetic Chemical, 52.2% of a copolymer poly(vinylpyrrolidone/dimethylaminoethyl methacrylate), available as "Copolymer 958" from GAF and 10% polyethylene glycol, available as Carbowax® 600 from Union Carbide.

The topcoat for each example contained 10% Tyzor® TE, a triethanolamine titanate chelate, and 10% polymethylmethacrylate beads, plus the varying ingredients described in the table below at 100%. Each of these examples was knife coated 75 µm thick on top of the bottomcoat and dried at about 95ºC for 120 s (2 min). This gave a dry coating weight of 0.08-0.10 g/m².

The transparencies were then evaluated by imaging a solid black filled rectangle on an Epson Color Stylus® printer using the transparencies print mode. The optical density of each image was then measured.

As can be seen from the data, the fluorocarbon of Example 38, the only nonionic fluorocarbon-type surfactant, provides excellent optical density and the anionic surfactants used in Comparative Examples C39-C45 do not.

Wilhelmy meter measurements were also performed for Example 38 and Comparative Examples C39-C45. As shown in the following table, the nonionic fluorocarbon type surfactant has the highest surface energy, with the two anionic surfactants having much lower surface energies at all three different concentrations.

Example 46

An ink jet recording sheet was prepared as follows. The substrate provided was a 100 µm white microvoided polyester with an opacity of 90%. A two layer ink jet coating system was applied thereto. The undercoat contained 29.6% of the polyvinyl alcohol, Airvol® 523, 5.2% of the polyvinyl alcohol Gohsenol® KPO6, 52.2% of the PVP/DMAEMA copolymer "Copolymer 958" and 10% of the polyethylene glycol Carbowax® 600 and 3% of a mordant having the structure disclosed above in Example 1. This layer was machine applied to give a dry coating weight of about 9.7 g/m2. The topcoat contained 77% Methocel® F50, 10% Tyzor® TE, 10% PMMA beads and 3% Zonyl® FSO. This layer was machine applied to give a dry coat weight of 0.81 g/m2. The inkjet recording sheet was dried at 121ºC for 60 s (1 min).

When printed on the Epson Stylus® printer using the media setting for special coated paper and the microweave print option, the images were of excellent quality at both 360 dpi and 720 dpi resolution.

Example 47

An ink jet recording sheet was prepared as follows. The substrate provided was PVDC primed polyester film. A two layer coating system was applied thereto. The undercoat contained 34% PVA blend, 52% Copolymer 958 and 7.8% Carbowax® 600, 1.4% Methocel® F50 and 3.8% mordant P134 having the structure disclosed in Example 1. This layer was machine applied to give a dry coating weight of about 9.7 g/m². The Topcoat was coated to a wet thickness of 50 µm and contained 41% hydroxypropylmethylcellulose (Methocel® F50), 39% acetylacetonate (Tyzor® GBA), 7.2% polyethylene glycol (Carbowax® 8000), 10% polymethylmethacrylate (PMMA) beads and 3% Zonyl® FSO: The inkjet recording sheet was dried at 121ºC for 60 s (1 min).

When printed on the Epson Stylus® printer, the density was 0.92.

Example 48

The undercoat was coated as described in Example C2 and a topcoat containing 34% zirconium triethanolamine chelate, 65% hydroxypropylmethylcellulose and 1% Zonyl® FSO was coated over the undercoat to a wet thickness of 75 µm and dried at 120ºC for 60 s (1 min). The black density was between 0.91 and 0.93.

Claims (10)

1. An uncrosslinked composition suitable for use as an inkjet recording medium comprising: a) at least one non-ionic surfactant of the fluorocarbon type selected from linear perfluorinated polyethoxylated alcohols, fluorinated alkylpolyoxyethylene alcohols and fluorinated alkyl alkoxylates, b) at least one metal chelate selected from titanate alkanolamines, titanate acetonates, aluminium alkanolamines and zirconium alkanolamines and c) at least one cellulose polymer selected from hydroxycellulose polymers and polymers of substituted hydroxycellulose, such a composition being crosslinkable when exposed to temperatures of at least 90ºC. 2. Composition according to claim 1, wherein the hydroxycellulose is selected from hydroxypropylmethylcellulose and hydroxypropylethylcellulose. 3. A sheet material for ink jet recording comprising a transparent substrate having two major surfaces, at least one major surface having applied thereto a composition according to claim 1 or 2, the composition having been crosslinked by application of heat to the substrate. 4. A web material for ink jet recording comprising an imageable two-layer coating system comprising: a) a thick absorbent backing comprising at least one crosslinkable polymeric component and b) an optically clear, thin top layer comprising a composition according to claim 1 or 2, wherein the top layer has been crosslinked by the application of heat to the substrate. 5. The ink jet recording sheet of claim 4, wherein the thick absorbent underlayer comprises: a) at least one crosslinkable polymeric component; b) at least one liquid-absorbing component comprising a water-absorbing polymer and c) 0 to 5% of a crosslinker. 6. The ink jet recording sheet according to claim 5, wherein the liquid absorbing component comprises a polymer selected from polyvinyl alcohol, copolymers of vinyl alcohol and vinyl acetate, polyvinyl formal, polyvinyl butyral, gelatin, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl starch, polyethyl oxazoline, polyethylene oxide, polyethylene glycol and polypropylene oxide. 7. The ink jet recording sheet of claim 6, wherein the polymeric liquid absorbing component comprises polyvinylpyrrolidone. 8. The ink jet recording sheet according to claim 5, wherein the crosslinker is a multifunctional aziridine selected from tris(β-(N-aziridinyl)propionate); pentaerythritol tris(β-(N-aziridinyl)propionate) and trimethylolpropane tris(β-(N-methylaziridinyl)propionate). 9. The ink jet recording sheet material according to any one of claims 3-5, wherein the substrate is transparent. 10. An ink jet recording sheet according to any one of claims 3-5, wherein the substrate is opaque.